This invention relates to a forming machine for parts using the stretching method, with a tool or form.
These machines are used notably in the field of aeronautics for the manufacture of fuselage parts for example or parts for the leading edges of the wings.
Such a machine is described in the document FR-2 650 205. This machine, or press, consists of an elongated frame which comprises at its central portion, a table accommodating the tool or form.
The part to be formed may be for example a sheet metal; this sheet metal is held between the claws of two jaws in order to be stretched, beyond its elastic limit, and to be embossed on the form.
These jaws are arranged transversally with respect to the frame, on either side of the tool and each of them is mobile longitudinally and vertically, by means of several pairs of oscillating jacks: quasi-horizontal jacks and quasi-vertical jacks.
The horizontal jacks are mobile in an angular section, on either side of the longitudinal horizontal plane under the effect of the vertical jacks, and the vertical jacks are, similarly, mobile in an angular sector on either side of a plane perpendicular to the longitudinal horizontal plane under the effect of the horizontal jacks. This capacity of movement of the jacks provides, for each jaw, a capacity of displacement practically in all directions.
In the document mentioned above, each jaw is guided with respect to the frame using oscillating props, laid out in the longitudinal and vertical median plane of the frame. Each prop is telescopic. It is hinged at one end of the frame and, on the side of the jaws, it is mobile in a U-shaped guide. The telescopic portion of the prop is integral with the jaw in order to maintain a point of the said jaw in the median vertical longitudinal guiding plane.
This invention provides an alternate solution to the guiding problem of the jaws with respect to the frame.
This solution enables to reduce the number of parts in motion on that machine and the jaws keep high freedom of movement, in particular, in the casing paths of the tool or form.
According to the invention, the machine or press consists of a horizontal frame provided at its central part with a tool or form, mounted transversally with, on either side of said tool, jaws each actuated by two pairs of oscillating jacks: a pair of horizontal jacks, anchored to the corresponding end of the said frame and a pair of vertical jacks anchored to the lower end of the central portion of the bracket-shaped frame, whereas each jaw and its cradle are guided with respect to said frame so that one of their points is held in a longitudinal and vertical plane of said frame, the retaining means of the said point of each jaw and cradle, in said vertical longitudinal plane, consist of guiding means provided on the one hand, directly on the roll of one of the control jacks and, on the other hand, on the frame, in order to maintain the axis of said roll in said vertical longitudinal plane.
The guiding jack is provided in the frame while remaining centered in the vertical longitudinal plane and its roll forms a kind of oscillating rail, by means, on the one hand, of its bottom which is hinged on a bracket below the central section of the frame, along an axis perpendicular to the vertical longitudinal plane and with translation immobilization and, on the other hand, by means of its mouth which is provided with diametrically opposed pads which co-operate with sliding surfaces arranged on the frame, which surfaces are in the form of plates arranged parallel to said vertical longitudinal plane.
The guiding jacks of the jaws consist of the vertical jacks situated for example on the same side of the frame, in the same vertical longitudinal guiding plane.
Each jaw is moreover hinged by its cradle, on the end of the rod of its guiding jack, by means of a spindle whose axis is perpendicular to said jack rod and centered on the guiding plane, i.e. the vertical longitudinal plane of the frame. Besides, the axis of the vertical guiding jack, for each jaw, is arranged so that it runs in the vicinity of the claws of said jaw.
The other control jacks of the jaws, i.e. the jacks other than the vertical jacks guiding said latter are linked to the frame and their respective jaws, by means of spherical plain bearings and/or cardan-type universal joints.
Still according to the invention, the frame comprises mainly a longitudinal structure comprising two large lateral caisson-shaped beams, linked together, and a bracket extending below the central portion of said structure, which bracket is provided with a sole enabling its anchoring on the slab, at the bottom of a pit, for example.
The structure in the form of beams and the bracket make up preferably, especially in the case of a very large press, two separate assemblies; this modular design enables to facilitate the transportation of said press, and said assemblies can be bolted together, for example, on site. Moreover, the upper section of the longitudinal structure forming the frame can be situated at ground level, for instance: in such case, the upper surface of the frame is provided at passage level of the rods of the vertical jacks, with mobile floorings which follow the movement of said rods, providing a certain safety to the operators liable to walk on said frame.